Publisher :
Place of publication :
Publication year : 2009
Thematic : Marine Resources
Language : English
Note
An ecosystem approach to the management of the marine environment has received considerable attention
over recent years. However, there are few examples which demonstrate its practical implementation.
Much of this relates to the history of existing marine monitoring and assessment programmes
which (for many countries) are sectoral, making it difficult to integrate monitoring data and knowledge
across programmes at the operational level.
To address this, a scientific expert group, under the auspices of the International Council for the Exploration
of the Sea (ICES), prepared a plan for how ICES could contribute to the development of an Integrated
Ecosystem Assessment (IEA) for the North Sea by undertaking a pilot study utilising marine
monitoring data. This paper presents the main findings arising from the expert group and in particular
it sets out one possible integrated approach for assessing the relative significance of environmental forcing
and fishing pressure on the ecological status of the North Sea, it then compares the findings with
assessments made of other Large Marine Ecosystems (LMEs).
We define the North Sea ecosystem on the basis of 114 state and pressure variables resolved as annual
averages between 1983 and 2003 and at the spatial scale of ICES rectangles. The paper presents results of
integrated time-series and spatial analysis which identifies and explains significant spatial and temporal
gradients in the data. For example, a significant shift in the status of the North Sea ecosystem (based upon
114 state-pressure variables) is identified to have occurred around 1993. This corresponds to previously
documented shifts in the environmental conditions (particularly sea surface temperature) and changes in
the distribution of key species of plankton (Calanus sp.), both reported to have occurred in 1989. The difference
in specific timing between reported regime shifts for the North Sea may be explained, in part, by
time-lag dependencies in the trophic structure of the ecosystem with shifts in higher trophic levels occurring
later than 1989.
By examining the connection (or relatedness) between ecosystem components (e.g. environment,
plankton, fish, fishery and seabirds) for the identified regime states (1983–1993; 1993–2003) we conclude
that both the North Sea pelagic and benthic parts of the ecosystem were predominantly top-down
(fishery) controlled between 1983 and 1993, whereas between 1993 and 2003 the pelagic stocks shifted
to a state responding mainly to bottom-up (environment) influences. However, for the demersal fish
stocks between 1993 and 2003 top-down (fishery) pressure dominated even though over this period significant
reductions in fishing pressure occurred. The present analysis, therefore, provides further evidence
in support of the need for precautionary management measures taken in relation to setting
fishery quotas.
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Encoded by : Pauline Carmel Joy Eje
